Someone with both a greater standard of all aspects of grammar (than most people) and the willingness to uphold said standards in all that (s)he says and writes, including but not limited to speaking in casual conversation and typing on the internet. Grammar Nazis are not constrained to the internet.
Zealous Grammar Nazis are also known to correct the grammar of other people when they feel the need to, although the act of correcting grammar does not necessarily denote someone as a Grammar Nazi. Someone who indulges in pointlessly correcting people, particularly nitpicking trivial mistakes, is more often a Grammar Troll. That's something else entirely.
True members of the Grammar Nazi Party will politely correct other people in a manner that does not shame the recipient and is always of mistakes that either change the meaning of the statement or are apparent that the recipient is ignorant of. Misuse of the apostrophe in "it's" and "its" and the misuse of homophones, however, are often corrected even if they do not apply to aforementioned standards.
As it has been mentioned that Grammar Nazis are not constrained to the internet, it should also be noted that Grammar Nazis interact in all languages that have codified rules of grammar (i.e. all official world languages). Some fictional languages, such as Klingon (Star Trek) and the Ancient Language (The Inheritance Cycle) are also included.
Zealous Grammar Nazis are also known to correct the grammar of other people when they feel the need to, although the act of correcting grammar does not necessarily denote someone as a Grammar Nazi. Someone who indulges in pointlessly correcting people, particularly nitpicking trivial mistakes, is more often a Grammar Troll. That's something else entirely.
True members of the Grammar Nazi Party will politely correct other people in a manner that does not shame the recipient and is always of mistakes that either change the meaning of the statement or are apparent that the recipient is ignorant of. Misuse of the apostrophe in "it's" and "its" and the misuse of homophones, however, are often corrected even if they do not apply to aforementioned standards.
As it has been mentioned that Grammar Nazis are not constrained to the internet, it should also be noted that Grammar Nazis interact in all languages that have codified rules of grammar (i.e. all official world languages). Some fictional languages, such as Klingon (Star Trek) and the Ancient Language (The Inheritance Cycle) are also included.
by tkdrocker806 December 26, 2014

An Asshat that normally trolls forums looking for posts to correct becuase they have nothing worthwild to add to the thread..
by Blake May 6, 2005

Some random douche:James is being a grammar nazi!
Jame:How about you graduate 2nd Grade and we'll talk
Jame:How about you graduate 2nd Grade and we'll talk
by Grammar Nazi November 5, 2015

Grammar Nazi: My head exploded after seeing this definition! I must correct all of his grammar mistakes or else I will die.
by tinycrate September 26, 2015

by Bleh November 23, 2002

by fuzzylane September 23, 2012

A native english-speaking person with an urge to correct every misspelled word, because they have a micropenis.
by Urban talker February 28, 2015
